quick tip if everyone in your party is facing in the very front of where the enemy is, it will really help your team more damage, distance differs in damage, everyone in the front = more damage everyone placed in the back = minimal damage
selling lubricant in araten and then buying leather from there and selling it to new serino, repeat it a few times and you shall make quite a bit of cash
on the main menu screen, there are grey blocks on the side that are darker as they reach the bottom, those blocks are checkpoints, click them and you won't have to completely retry all the levels